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Low biodegradability of graphene derivatives and related health risks are the main limiting factors for their in vivo biomedical applications. Here, we present the synthesis of enzyme-functionalized graphene sheets with self-degrading properties under physiological conditions and their applications in Tumor therapy. The synergistic enzyme cascade glucose oxidase and myeloperoxidase are covalently conjugated to the surface of graphene sheets and two-dimensional (2D) platforms are obtained that can produce sodium hypochlorite from glucose. The enzyme-functionalized graphene sheets with up to 289 nm average size are degraded into small pieces (≤40 nm) by incubation under physiological conditions for 24 h. Biodegradable graphene sheets are further loaded with doxorubicin and their ability for Tumor therapy is evaluated in vitro and in vivo. The laser-triggered release of doxorubicin in combination with the enzymatic activity of the functionalized graphene sheets results in a synergistic antitumor activity.
Taking advantage of their neutrophil-like activity, fast biodegradability, high photo- and chemotherapeutic effects, the novel two-dimensional nanoplatforms can be used for tumor therapeutic applications.
An understanding of the interactions of 2D nanomaterials with pathogens is of vital importance to developing and controlling their antimicrobial properties. In this work, the interaction of functionalized graphene with tunable hydrophobicity and bacteria is investigated. Poly-(ethylene glycol)-block-(poly-N-isopropylacrylamide) copolymer (PEG-b-PNIPAM) with the triazine joint point was attached to the graphene Surface by a nitrene [2 + 1] cycloaddition reaction. By thermally switching between hydrophobic and hydrophilic states, functionalized graphene sheets were able to bind to bacteria. Bacteria were eventually disrupted when the functionality was switched to the hydrophobic state. On the basis of measuring the different microscopy methods and a live/dead viability assay, it was found that Escherichia coli (E. coli) bacteria are more susceptible to hydrophobic interactions than B. cereus bacteria, under the same conditions. Our investigations confirm that hydrophobic interaction is one of the main driving forces at the presented graphene/bacteria interfaces and promotes the antibacterial activity of graphene derivatives significantly.
Understanding the mechanism of interactions of nanomaterials at biointerfaces is a crucial issue to develop new antimicrobial vectors. In this work, a series of water-soluble fullerene-polyglycerol sulfates (FPS) with different fullerene/polymer weight ratios and varying numbers of polyglycerol sulfate branches are synthesized, characterized, and their interactions with two distinct surfaces displaying proteins involved in target cell recognition are investigated. The combination of polyanionic branches with a solvent exposed variable hydrophobic core in FPS proves to be superior to analogs possessing only one of these features in preventing interaction of vesicular Stomatitis virus coat glycoprotein (VSV-G) with baby hamster kidney cells serving as a model of host cell. Interference with L-selectin-ligand binding is dominated by the negative charge, which is studied by two assays: a competitive surface plasmon resonance (SPR)-based inhibition assay and the leukocyte cell (NALM-6) rolling on ligands under flow conditions. Due to possible intrinsic hydrophobic and electrostatic effects of synthesized compounds, pico- to nanomolar half maximal inhibitory concentrations (IC50) are achieved. With their highly antiviral and anti-inflammatory properties, together with good biocompatibility, FPS are promising candidates for the future development towards biomedical applications.
Light- and small-angle neutron scattering as well as cryo-transmission electron microscopy (cryo-TEM) studies were performed to probe the structure of J-aggregates formed by a series of achiral dye molecules of the 5,5',6,6'-tetrachlorobenzimidacarbocyanine chromophore having 1,1'-dialkyl substituents combined with 3,3'-bis(4-sulfobutyl)-3,3'-bis(4-carboxybutyl) or 3,3'-bis(3-carboxypropyl) substituents. Assemblies that display a dependence on the substituents different complex supramolecular structures of nanometer-to-micrometer size have been directly visualized by cryo-TEM. The superstructures span from monomolecular layers formed by the 1,1'-diethyl-3,3'-bis(4-sulfobutyl) derivative and stacks of bilayer ribbons in the case of the 1,1'-dioctyl-3,3'-bis(4-carboxybutyl) derivative to twisted ropelike structures for the chiral aggregate of the 1,1'-dioctyl-3,3'-bis(3-carboxypropyl)-substituted chromophore.
Surfactant-induced changes of morphology of J-aggregates: Superhelix-to-tubule transformation
(2000)
The morphology of the J-aggregates formed after the addition of ionic surfactants into solutions of the 3,3'-bis(3-carboxypropyl)-5,5',6,6'-tetrachloro-1,1'-dioctylbenzimidacarbocyanine dye (C8O3) was characterized by absorption and circular dichroism spectroscopy, cryogenic temperature transmission electron microscopy, scanning force microscopy, and small-angle neutron scattering. The optical activity of the C8O3 J-aggregates, existing in aqueous solution as superhelices composed of tubular single strands, disappears upon addition of both cationic and anionic surfactants. This is accompanied by distinct spectral changes in the visible region as well as changes of the aggregates' morphology. The anionic surfactant sodium dodecyl sulfate induces the formation of single-walled tubules of 15 nm diameter and 300-600 nm length, which completely transform after several days into thick multilamellar tubes of micrometer length. The cationic surfactant trimethyltetradecylammonium bromide first produces vesicles that later transform again into tubular aggregates of nanometer thickness and micrometer length.